Chapter 19 Configuring Cdp; Understanding Cdp - Cisco Catalyst 3750 Software Configuration Manual

Metro switch

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Configuring CDP

This chapter describes how to configure Cisco Discovery Protocol (CDP) on the Catalyst 3750 Metro

For complete syntax and usage information for the commands used in this chapter, refer to the command

reference for this release and the Cisco IOS Configuration Fundamentals Command Reference for

Release 12.1.

This chapter consists of these sections:

CDP is a device discovery protocol that runs over Layer 2 (the data link layer) on all Cisco-manufactured

devices (routers, bridges, access servers, and switches) and allows network management applications to

discover Cisco devices that are neighbors of already known devices. With CDP, network management

applications can learn the device type and the Simple Network Management Protocol (SNMP) agent

address of neighboring devices running lower-layer, transparent protocols. This feature enables

applications to send SNMP queries to neighboring devices.

CDP runs on all media that support Subnetwork Access Protocol (SNAP). Because CDP runs over the

data-link layer only, two systems that support different network-layer protocols can learn about each

Each CDP-configured device sends periodic messages to a multicast address, advertising at least one

address at which it can receive SNMP messages. The advertisements also contain time-to-live, or

holdtime information, which is the length of time a receiving device holds CDP information before

discarding it. Each device also listens to the messages sent by other devices to learn about neighboring

The switch supports CDP version 2.

Understanding CDP, page 19-1

Configuring CDP, page 19-2

Monitoring and Maintaining CDP, page 19-5

C H A P T E R

Catalyst 3750 Metro Switch Software Configuration Guide

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